journald: do not free space when disk space runs low
Before, journald would remove journal files until both MaxUse= and KeepFree= settings would be satisfied. The first one depends (if set automatically) on the size of the file system and is constant. But the second one depends on current use of the file system, and a spike in disk usage would cause journald to delete journal files, trying to reach usage which would leave 15% of the disk free. This behaviour is surprising for the user who doesn't expect his logs to be purged when disk usage goes above 85%, which on a large disk could be some gigabytes from being full. In addition attempting to keep 15% free provides an attack vector where filling the disk sufficiently disposes of almost all logs. Instead, obey KeepFree= only as a limit on adding additional files. When replacing old files with new, ignore KeepFree=. This means that if journal disk usage reached some high point that at some later point start to violate the KeepFree= constraint, journald will not add files to go above this point, but it will stay (slightly) below it. When journald is restarted, it forgets the previous maximum usage value, and sets the limit based on the current usage, so if disk remains to be filled, journald might use one journal-file-size less on each restart, if restarts happen just after rotation. This seems like a reasonable compromise between implementation complexity and robustness.
This commit is contained in:
Zbigniew Jędrzejewski-Szmek
parent
b948018034
commit
348ced9097
|
|
@ -250,20 +250,35 @@
|
|||
<para><varname>SystemMaxUse=</varname>
|
||||
and <varname>RuntimeMaxUse=</varname>
|
||||
control how much disk space the
|
||||
journal may use up at
|
||||
maximum. Defaults to 10% of the size
|
||||
of the respective file
|
||||
system. <varname>SystemKeepFree=</varname>
|
||||
and
|
||||
journal may use up at maximum.
|
||||
<varname>SystemKeepFree=</varname> and
|
||||
<varname>RuntimeKeepFree=</varname>
|
||||
control how much disk space
|
||||
systemd-journald shall always leave
|
||||
free for other uses. Defaults to 15%
|
||||
of the size of the respective file
|
||||
system. systemd-journald will respect
|
||||
both limits, i.e. use the smaller of
|
||||
the two values.
|
||||
<varname>SystemMaxFileSize=</varname>
|
||||
systemd-journald shall leave free for
|
||||
other uses.
|
||||
<command>systemd-journald</command>
|
||||
will respect both limits and use the
|
||||
smaller of the two values.</para>
|
||||
|
||||
<para>The first pair defaults to 10%
|
||||
and the second to 15% of the size of
|
||||
the respective file system. If the
|
||||
file system is nearly full and either
|
||||
<varname>SystemKeepFree=</varname> or
|
||||
<varname>RuntimeKeepFree=</varname> is
|
||||
violated when systemd-journald is
|
||||
started, the value will be raised to
|
||||
percentage that is actually free. This
|
||||
means that if before there was enough
|
||||
free space and journal files were
|
||||
created, and subsequently something
|
||||
else causes the file system to fill
|
||||
up, journald will stop using more
|
||||
space, but it'll will not removing
|
||||
existing files to go reduce footprint
|
||||
either.</para>
|
||||
|
||||
<para><varname>SystemMaxFileSize=</varname>
|
||||
and
|
||||
<varname>RuntimeMaxFileSize=</varname>
|
||||
control how large individual journal
|
||||
|
|
|
|||
|
|
@ -37,6 +37,7 @@
|
|||
|
||||
typedef struct JournalMetrics {
|
||||
uint64_t max_use;
|
||||
uint64_t use;
|
||||
uint64_t max_size;
|
||||
uint64_t min_size;
|
||||
uint64_t keep_free;
|
||||
|
|
|
|||
|
|
@ -150,7 +150,6 @@ static int journal_file_empty(int dir_fd, const char *name) {
|
|||
int journal_directory_vacuum(
|
||||
const char *directory,
|
||||
uint64_t max_use,
|
||||
uint64_t min_free,
|
||||
usec_t max_retention_usec,
|
||||
usec_t *oldest_usec) {
|
||||
|
||||
|
|
@ -164,7 +163,7 @@ int journal_directory_vacuum(
|
|||
|
||||
assert(directory);
|
||||
|
||||
if (max_use <= 0 && min_free <= 0 && max_retention_usec <= 0)
|
||||
if (max_use <= 0 && max_retention_usec <= 0)
|
||||
return 0;
|
||||
|
||||
if (max_retention_usec > 0) {
|
||||
|
|
@ -309,8 +308,7 @@ int journal_directory_vacuum(
|
|||
}
|
||||
|
||||
if ((max_retention_usec <= 0 || list[i].realtime >= retention_limit) &&
|
||||
(max_use <= 0 || sum <= max_use) &&
|
||||
(min_free <= 0 || (uint64_t) ss.f_bavail * (uint64_t) ss.f_bsize >= min_free))
|
||||
(max_use <= 0 || sum <= max_use))
|
||||
break;
|
||||
|
||||
if (unlinkat(dirfd(d), list[i].filename, 0) >= 0) {
|
||||
|
|
|
|||
|
|
@ -23,4 +23,4 @@
|
|||
|
||||
#include <inttypes.h>
|
||||
|
||||
int journal_directory_vacuum(const char *directory, uint64_t max_use, uint64_t min_free, usec_t max_retention_usec, usec_t *oldest_usec);
|
||||
int journal_directory_vacuum(const char *directory, uint64_t max_use, usec_t max_retention_usec, usec_t *oldest_usec);
|
||||
|
|
|
|||
|
|
@ -158,9 +158,18 @@ static uint64_t available_space(Server *s, bool verbose) {
|
|||
}
|
||||
|
||||
ss_avail = ss.f_bsize * ss.f_bavail;
|
||||
avail = ss_avail > m->keep_free ? ss_avail - m->keep_free : 0;
|
||||
|
||||
s->cached_available_space = MIN(m->max_use, avail) > sum ? MIN(m->max_use, avail) - sum : 0;
|
||||
/* If we reached a high mark, we will always allow this much
|
||||
* again, unless usage goes above max_use. This watermark
|
||||
* value is cached so that we don't give up space on pressure,
|
||||
* but hover below the maximum usage. */
|
||||
|
||||
if (m->use < sum)
|
||||
m->use = sum;
|
||||
|
||||
avail = LESS_BY(ss_avail, m->keep_free);
|
||||
|
||||
s->cached_available_space = LESS_BY(MIN(m->max_use, avail), sum);
|
||||
s->cached_available_space_timestamp = ts;
|
||||
|
||||
if (verbose) {
|
||||
|
|
@ -168,13 +177,14 @@ static uint64_t available_space(Server *s, bool verbose) {
|
|||
fb4[FORMAT_BYTES_MAX], fb5[FORMAT_BYTES_MAX];
|
||||
|
||||
server_driver_message(s, SD_MESSAGE_JOURNAL_USAGE,
|
||||
"%s journal is using %s (max %s, leaving %s of free %s, current limit %s).",
|
||||
"%s journal is using %s (max allowed %s, "
|
||||
"trying to leave %s free of %s available → current limit %s).",
|
||||
s->system_journal ? "Permanent" : "Runtime",
|
||||
format_bytes(fb1, sizeof(fb1), sum),
|
||||
format_bytes(fb2, sizeof(fb2), m->max_use),
|
||||
format_bytes(fb3, sizeof(fb3), m->keep_free),
|
||||
format_bytes(fb4, sizeof(fb4), ss_avail),
|
||||
format_bytes(fb5, sizeof(fb5), MIN(m->max_use, avail)));
|
||||
format_bytes(fb5, sizeof(fb5), s->cached_available_space + sum));
|
||||
}
|
||||
|
||||
return s->cached_available_space;
|
||||
|
|
@ -379,7 +389,7 @@ void server_vacuum(Server *s) {
|
|||
if (s->system_journal) {
|
||||
char *p = strappenda("/var/log/journal/", ids);
|
||||
|
||||
r = journal_directory_vacuum(p, s->system_metrics.max_use, s->system_metrics.keep_free, s->max_retention_usec, &s->oldest_file_usec);
|
||||
r = journal_directory_vacuum(p, s->system_metrics.max_use, s->max_retention_usec, &s->oldest_file_usec);
|
||||
if (r < 0 && r != -ENOENT)
|
||||
log_error("Failed to vacuum %s: %s", p, strerror(-r));
|
||||
}
|
||||
|
|
@ -387,7 +397,7 @@ void server_vacuum(Server *s) {
|
|||
if (s->runtime_journal) {
|
||||
char *p = strappenda("/run/log/journal/", ids);
|
||||
|
||||
r = journal_directory_vacuum(p, s->runtime_metrics.max_use, s->runtime_metrics.keep_free, s->max_retention_usec, &s->oldest_file_usec);
|
||||
r = journal_directory_vacuum(p, s->runtime_metrics.max_use, s->max_retention_usec, &s->oldest_file_usec);
|
||||
if (r < 0 && r != -ENOENT)
|
||||
log_error("Failed to vacuum %s: %s", p, strerror(-r));
|
||||
}
|
||||
|
|
|
|||
|
|
@ -189,7 +189,7 @@ static void test_skip(void (*setup)(void)) {
|
|||
if (arg_keep)
|
||||
log_info("Not removing %s", t);
|
||||
else {
|
||||
journal_directory_vacuum(".", 3000000, 0, 0, NULL);
|
||||
journal_directory_vacuum(".", 3000000, 0, NULL);
|
||||
|
||||
assert_se(rm_rf_dangerous(t, false, true, false) >= 0);
|
||||
}
|
||||
|
|
@ -274,7 +274,7 @@ static void test_sequence_numbers(void) {
|
|||
if (arg_keep)
|
||||
log_info("Not removing %s", t);
|
||||
else {
|
||||
journal_directory_vacuum(".", 3000000, 0, 0, NULL);
|
||||
journal_directory_vacuum(".", 3000000, 0, NULL);
|
||||
|
||||
assert_se(rm_rf_dangerous(t, false, true, false) >= 0);
|
||||
}
|
||||
|
|
|
|||
|
|
@ -126,7 +126,7 @@ static void test_non_empty(void) {
|
|||
if (arg_keep)
|
||||
log_info("Not removing %s", t);
|
||||
else {
|
||||
journal_directory_vacuum(".", 3000000, 0, 0, NULL);
|
||||
journal_directory_vacuum(".", 3000000, 0, NULL);
|
||||
|
||||
assert_se(rm_rf_dangerous(t, false, true, false) >= 0);
|
||||
}
|
||||
|
|
@ -165,7 +165,7 @@ static void test_empty(void) {
|
|||
if (arg_keep)
|
||||
log_info("Not removing %s", t);
|
||||
else {
|
||||
journal_directory_vacuum(".", 3000000, 0, 0, NULL);
|
||||
journal_directory_vacuum(".", 3000000, 0, NULL);
|
||||
|
||||
assert_se(rm_rf_dangerous(t, false, true, false) >= 0);
|
||||
}
|
||||
|
|
|
|||
|
|
@ -117,6 +117,13 @@ static inline size_t ALIGN_TO(size_t l, size_t ali) {
|
|||
_a < _b ? _a : _b; \
|
||||
})
|
||||
|
||||
#define LESS_BY(A,B) \
|
||||
__extension__ ({ \
|
||||
typeof(A) _A = (A); \
|
||||
typeof(B) _B = (B); \
|
||||
_A > _B ? _A - _B : 0; \
|
||||
})
|
||||
|
||||
#ifndef CLAMP
|
||||
#define CLAMP(x, low, high) \
|
||||
__extension__ ({ \
|
||||
|
|
|
|||
Loading…
Reference in New Issue